Hand tool apparatus for orbital drilling

ABSTRACT

A hand tool apparatus uses a cutting tool with a first width and a tool axis to machine a hole in an object. The hole has a second width at least as large as the first width of the cutting tool. The tool axis passes through a predetermined point on a surface of the object. The apparatus includes an actuating assembly including a housing. The housing contains an axial feed mechanism configured for moving the cutting tool in an axial direction, a spindle motor configured for rotating the cutting tool about the tool axis, and a radial offset mechanism. The radial offset mechanism is configured for moving the cutting tool such that the tool axis is offset from a principal axis. A motor is configured for rotating the axial feed mechanism and the cutting tool about the principal axis.

This is a continuation of application Ser. No. 09/388,419 now U.S. Pat.No. 6,382,890 filed Sep. 1, 1999.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hand tool for cutting a hole in anobject, and, more particularly, a hand tool for cutting a hole that hasa larger diameter than the diameter of the cutting tool.

2. Description of the Related Art

U.S. Pat. No. 5,641,252 discloses a method for machining holes in afiber reinforced composite material by using at least one cutting toolwith wear resistant surface positioned eccentrically in relation to acentral axis. The material is machined simultaneously in both an axialand a radial direction by causing the tool to move axially whilerotating not only about its own axis, but also eccentrically about thecentral axis. In accordance with one particular characterizing featureof the invention, the workpiece is oriented in such a way that the axisof rotation of the tool is essentially orthogonal in relation to thelongitudinal directions of the fibers in the immediate vicinity of thepoint where the tool meets the working surface. The diameter of thecutting tool is substantially smaller than the diameter of the hole thatis produced. The eccentric rotary motion is generally a strictly rotarymotion, i.e., it is executed with a constant distance between thecentral axis and the axis of rotation of the cutting tool. This distancebetween the central axis and the axis of rotation of the cutting toolcan be increased by linear increments as the eccentric rotary motioncontinues.

This known method has a number of substantial advantages as comparedwith generally familiar techniques. For example, the method permits theproduction of holes without strength reducing damage. Also, the methodpermits the production of holes free from damage without having topreform a hole. Further, the method permits the production of holes totight tolerances. The dimensional accuracy of the hole is determinedsubstantially by the accuracy of the positioning of the tool relative tothe central axis. The requirements imposed on the geometry of thecutting tool are not particularly high, on the other hand, since everyindividual tool is simply calibrated before use. Additionally, themethod prevents the tool from becoming blocked. Since the diameter ofthe tool is substantially smaller than that of the hole, the methodpermits material removed by cutting to be carried away by simple means,such as with compressed air. The method also permits effective coolingof the tool and the edge of the hole. Yet another advantage is that themethod substantially reduces the cost of wear compared to previouslydisclosed methods, due to the tool being coated with a wear resistantmaterial, such as diamond coating. Moreover, this method also offersadvantages when machining other materials such as metals.

U.S. patent application Ser. No. 09/092,467 discloses a spindle unitthat includes a spindle motor that is rotatable about a principal axis.The spindle motor includes a tool holder having a tool axissubstantially parallel to the principal axis. The tool holder isrotatable about the tool axis. An axial actuator is configured formoving the spindle motor in an axial feed direction substantiallyparallel to each of the principal axis and the tool axis. A radialactuator adjusts a radial distance between the principal axis and thetool axis. This spindle unit can be mounted in a stationary machine suchas a CNC machine, robot or a simple rig.

PCT application PCT/SE94/00085 discloses a hand tool machine formachining holes according to the above described technique. Thisdisclosure relates to a hand machine for making holes in an object madeof composite fibers, preferably with a curved surface. The center axisof the hole passes through a predetermined point on the surface of theobject and is oriented in a certain direction relative to thelongitudinal direction of the fibers of the object which are close tothe point. The machine includes, in combination, a tool holder rotatingabout its own axis and a principal axis, a device for adjusting the axisof rotation of the tool holder in the normal direction of the surface atthe point, a device for axial feeding of the tool holder relative to theobject, a device for adjusting the radial distance between the principalaxis and the axis of rotation of the tool holder, and a device fortaking up the forces and moments between the machine and the object thatresult from the making of the holes.

Although this aforementioned disclosure outlines some principles, thedisclosed hand tool does not offer a feasible and practical solution.One obvious limitation is that the disclosed concepts do not present asolution for the power supply and therefore their potential forrealization must be questioned. One basic requirement for a hand tool islight-weight and user friendliness. The disclosed concepts do notprovide a compact integrated light-weight design. Furthermore, theillustrated concepts show solutions which require a very long tooloverhang, which is a severe limitation due to the radial cutting force,which creates a bending moment on the cutting tool.

When machining holes according to the proposed method, i.e., bypositioning the tool eccentrically in relation to a cental axis andmachining simultaneously in both an axial and radial direction bycausing the tool to move axially and to rotate not only about its ownaxis, but also eccentrically about a central axis, the tip of the toolis subjected to both an axial force and a radial force. The radial forcecreates bending moment on the tool, the magnitude of which is dependenton both the magnitude of the force and on the length of the tooloverhang (moment arm). It is desirable to minimize the bending momentfor optimal machining accuracy. This can be achieved by minimizing thetool overhang, i.e., the free length of the tool. The conceptsillustrated in PCT/SE94/00085 show situations where the tool overhang isdetermined by the thickness of the hole template and by the thickness ofthe workpiece. Since the thickness of the template may be substantial,the tool overhang may be accordingly substantial.

SUMMARY OF THE INVENTION

The present invention provides a hand tool apparatus using a cuttingtool to machine a hole in an object such that the hole has a width atleast as large as the width of the cutting tool. The center line of thehole passes through a predetermined point on the surface of the object.Moreover, the present invention provides a compact and lightweight handtool apparatus for machining holes in a flat or curved object of anymaterial by rotating a cutting tool about its own axis and about aprincipal axis while simultaneously feeding in the axial direction. Alightweight and compact apparatus is achieved by integrating a radialoffset mechanism, spindle motor and axial feed mechanism in a sameactuating assembly package, which rotates about a principal axis.

The invention comprises, in one form thereof, a hand tool apparatususing a cutting tool with a first width and a tool axis to machine ahole in an object. The hole has a second width at least as large as thefirst width of the cutting tool. The tool axis passes through apredetermined point on a surface of the object. The apparatus includesan actuating assembly including a housing. The housing contains an axialfeed mechanism configured for moving the cutting tool in an axialdirection, a spindle motor configured for rotating the cutting toolabout the tool axis, and a radial offset mechanism. The radial offsetmechanism is configured for moving the actuating assembly in a radialdirection such that the tool axis is offset from a principal axis. Amotor is configured for rotating said actuating assembly about theprincipal axis.

An advantage of the present invention is that the hand tool is morelightweight and compact than the previous devices.

Another advantage is that the tool overhang is minimized, therebyreducing the bending moment on the cutting tool.

Yet another advantage is that the tool can be mounted into the toolholder from the rear, thereby allowing the tool holder to have a conicalshape which minimizes the required diameter of the holes in thetemplate.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention,and the manner of attaining them, will become more apparent and theinvention will be better understood by reference to the followingdescription of embodiments of the invention taken in conjunction withthe accompanying drawings, wherein:

FIG. 1 is a top, sectional view of one embodiment of a pneumaticportable drill of the present invention;

FIG. 2 is a top, sectional view of the tool assembly and a portion ofthe actuating assembly of the pneumatic portable drill of FIG. 1;

FIG. 3 is a rear, sectional view taken along line 3—3 in FIG. 1;

FIG. 4A is a side, sectional view of one embodiment of a templateassembly of the portable drill of FIG. 1;

FIG. 4B is a rear view of the template assembly of FIG. 4A;

FIG. 5A is a side, sectional view of another embodiment of a templateassembly of the pneumatic portable drill of FIG. 1;

FIG. 5B is a rear view of the template assembly of FIG. 5A;

FIG. 6 is a side view of the pneumatic portable drill of FIG. 1;

FIG. 7 is a rear view of the pneumatic portable drill of FIG. 1;

FIG. 8A is a schematic, sectional view, taken along line 3—3 of FIG. 1,of the relative positions of the tool, inner sleeve and outer sleeve;

FIG. 8B is a view similar to FIG. 8A, with the inner sleeve rotated 90°counterclockwise relative to its position in FIG. 8A; and

FIG. 8C is a view similar to FIG. 8A, with the inner sleeve rotated 180°counterclockwise relative to its position in FIG. 8A.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrates one preferred embodiment of the invention, in one form, andsuch exemplifications are not to be construed as limiting the scope ofthe invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings and particularly to FIG. 1, there is showna hand tool apparatus in the form of a pneumatic portable drill 10including an actuating assembly 12, eccentric rotation mechanism 14,tool assembly 16, template assembly 18, axial positioning mechanism 20(FIG. 6), stroke adjustment mechanism 22 and an axial feed mechanism 24.

Actuating assembly 12 includes a spindle motor 26, and a radial offsetmechanism 28 (FIG. 3), all contained within a single housing 29. Radialoffset mechanism 28 includes a concentric cylindrical inner sleeve 30positioned in a concentric cylindrical outer sleeve 32. Inner sleeve 30and outer sleeve 32 are rotatable relative to each other. An axle orshaft 34 of spindle motor 26 extends through a clutch 36 and isrotatably mounted in inner sleeve 30.

Eccentric rotation mechanism 14 includes a motor 38 for rotatingactuating assembly 12 and thereby tool assembly 16 about a principalaxis 40.

Template assembly 18 includes a sleeve 42 (FIG. 4A) with a flange 44which is in contact with the surface of a work piece 46. A center axis48 of sleeve 42 is oriented substantially perpendicular to the surfaceof work piece 46. Sleeve 42 and flange 44 are fastened to a template 50by bolted joints 52. Tool assembly 16 is locked onto sleeve 42 by use ofa bayonet socket 54, whereby the axis of rotation of drill 10 areoriented substantially perpendicular to the surface of work piece 46.

In another embodiment, a sleeve 56 (FIG. 5A) is also oriented in thehole in template 50 such that axis of rotation 48 of sleeve 56 issubstantially perpendicular to the surface of work piece 46. Sleeve 56can be fixed to template 50 by use of a threaded joint, frictional jointor adhesive joint. Portable drill 10 is then locked onto sleeve 56 byuse of a bayonet socket 54, as shown in FIG. 1, whereby the axes ofrotation are oriented substantially perpendicular to the surface of workpiece 46.

Tool assembly 16 includes a cutting tool 58, a tool holder 60 and ascrew 62. To minimize the tool overhang, template 50 is designed suchthat tool holder 60 can be fed through the holes in template 50. In suchcase, it is desired that tool holder 60 have a small outer diameter,since in many situations it is required to machine multiple holes inwork piece 46 with relatively short spacing distances between the holes.In order to accommodate all holes, the holes in template 50 can not bemade arbitrarily large to make room for tool holder 60. Therefore, it isdesirable for tool holder 60 to require as little space as possible.This is made possible by tool holder 60 and cutting tool 58 beingprovided with conical surfaces. Cutting tool 58 is mounted in toolholder 60 from the rear end and then tightened by screw 62 inside toolholder 60. By this concept, it is possible to obtain a space savingsolution which allows the feeding of tool holder 60 through the holes intemplate 50 without requiring that the template holes be too large.

Although the aforementioned tool holder concept offers a space savingadvantage, which allows feeding of tool holder 60 through template 50without requiring very large holes in template 50, the spacing betweenthe holes in work piece 46 may still be too small for the embodiment ofFIGS. 1 and 5. In such case, drill 10 is locked to an alternative fixingdevice (FIG. 4B) which is fixed in template 50 by two screws 52 in twoholes located a distance away from the main hole. Thus the holes intemplate 50 may be integrated, as in FIG. 4B, which is suitable in acase where the spacing between the holes in template 50 is small.

Axial positioning mechanism 20 includes a threaded ring 64 and a scale66. It is desirable to roughly position the tip of cutting tool 58 acertain distance from work piece 46 as shown in FIG. 1. This is achievedby threaded ring 64 and is made possible in that housing 29 of portabledrill 10 is separated at ring 64 into a front portion 65 and a rearportion 67. By turning ring 64, front portion 65 of drill housing 29moves forward or backward, which movement is indicated by scale 66.

Stroke adjustment mechanism 22 includes a ring 68 (FIG. 7), a rod 70, alock screw 72, a projection 74, an arm or latch 76 and a returnmechanism 78. The stroke length of the machining operation is adjustedby mechanism 22. Ring 68 is rotatably attached to the drill housing. Onring 68 is fastened a rod 70. Rod 70 is provided with a slot (not shown)such that its axial position is adjustable. The desired position isfixed by lock screw 72. Projection 74, fixedly attached to rod 70,contacts arm 76 of return mechanism 78 and thereby forces drill 10 tomake a return stroke after the contact.

In operation, axial feed mechanism 24 moves actuating assembly 12, andthereby cutting tool 58 in an axial feed direction, and spindle motor 26rotates cutting tool 58 about its own axis 80. Motor 38 rotatesactuating assembly 12 and thereby cutting tool 58 about principle axis40.

An axial feed motion directed towards work piece 46 is provided bysupplying compressed air in a circumferential cavity 82. As actuatingassembly 12 moves forward it forces oil, stored in anothercircumferential cavity 84, to flow through a radial hole 86 via an axialhole 88, another radial hole 90, and hole 92 into space 94 of cylinder96, which contains oil. A piston 98 then moves to the right in FIG. 1 inorder to allow for the volume increase. Thus provided is a hydrauliclydamped axial movement.

The speed of the axial movement can be controlled by adjusting theposition of a needle 100 in relation to hole 92. An axial feed motiondirected away from work piece 46 (return stroke) is achieved bysupplying compressed air into space 102, which contains air via achannel 104. The pressure increase in cylinder 96 due to the returnstroke causes a valve 106 to open and oil to flow back into cavity 84and thereby create a pressure increase, which causes actuating assembly12 to move away from work piece 46. This design allows for a fasterreturn stroke as compared to the forward feeding movement.

Air is supplied to spindle motor 26 through openings 108 in the wallelement of outer sleeve 32 of actuating assembly 12. The air then flowsin channel 110 to the rear end of spindle motor 26 and then throughspindle motor 26 to cause rotation of shaft 34. The return flow is thendirected through outlet 112 out to the open air. Outlet 112 rotateseccentrically in relation to the center axis of spindle motor 26. At therear end is arranged a sealing 114 and an end piece 116 for reducing thesound level.

Outer sleeve 32 is turnable or rotatable relative to inner sleeve 30,and thereby the axis of rotation 80 of cutting tool 58 and principalaxis 40 can be varied from zero (FIG. 8A) to a maximum value (FIG. 8C)by a relative rotation of 180° between the two sleeves 30, 32. FIG. 8Ashows a case where a 12 millimeter tool 58 is in zero offset position.FIG. 8C shows a case where tool 58 is in its maximum radial offsetposition, i.e., tool 58 is offset two millimeters in order to machine a16 millimeter hole.

The relative movement between sleeves 30, 32 is achieved by turning ascrew 118 (FIG. 3). A stop screw 120 locks sleeves 30 and 32 in adesired position. In order to adjust the offset, front portion 65 ofhousing 29 is removed by unlocking a tightening ring 122.

In order to rotate actuating assembly 12 and thereby cutting tool 58about a principal axis 40, gear wheels 124, 126 transfer the rotation ofmotor 38 to actuating assembly 12. Since tool holder 60 is connected toinner sleeve 30 of actuating assembly 12, tool holder 60 and cuttingtool 58 are forced into a rotation about principal axis 40.

Air is supplied through an opening 128. The speed of motor 38 iscontrolled by adjusting a needle 130 in opening 128. The outlet of theair supplied to motor 38 is not shown.

While this invention has been described as having a preferred design,the present invention can be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains and which fallwithin the limits of the appended claims.

What is claimed is:
 1. A hand tool apparatus for using a cutting toolwith a first width and a tool axis to machine a hole in an object, thehole having a second width that is larger than the first width of thecutting tool, the tool axis passing through a predetermined point on asurface of the object, said apparatus comprising: a housing; a pneumaticaxial feed mechanism contained in said housing and configured for movingthe cutting tool in an axial direction; a pneumatic actuating assemblycontained in said housing and comprising: a first motor configured forrotating the cutting tool about the tool axis; and a radial offsetmechanism configured for moving said cutting tool in a radial directionsuch that the tool axis is offset from a principal axis, said offsetmechanism including an outer cylindrical sleeve and an inner cylindricalsleeve rotatably supported in an eccentric hole in the outer sleeve; anda second motor fixedly contained in the housing and configured forrotating said pneumatic actuating assembly and the cutting tool aboutthe principal axis, said second motor disposed radially outwardly of andin substantially side by side relation with said first motor relative tosaid principal axis such that said first and second motors each extendlongitudinally over an axial linear extent such that there is asubstantial amount of overlap of the axial linear extents.
 2. The handtool apparatus of claim 1, wherein said first motor and said radialoffset mechanism are formed integrally with said axial feed mechanism.3. The hand tool apparatus of claim 1, wherein said first motorcomprises a pneumatic spindle motor.
 4. The hand tool apparatus of claim1, wherein said axial feed mechanism comprises a pneumatic axial feedmechanism.
 5. The hand tool apparatus of claim 1, wherein the secondmotor is configured to rotate the pneumatic actuating assembly by meansof a first gear wheel associated with the second motor, which first gearwheel is used for rotating a second gear wheel associated with thepneumatic actuating assembly, said second gear wheel being axiallydisplaceable relative to the first gear wheel.
 6. A hand tool apparatusfor using a cutting tool with a first width and a tool axis to machine ahole in an object, the hole having a second width that is larger thanthe first width of the cutting tool, the tool axis passing through apredetermined point on a surface of the object, said apparatuscomprising: a housing; a pneumatic axial feed mechanism contained insaid housing and configured for moving the cutting tool in an axialdirection; a pneumatic actuating assembly contained in said housing andcomprising: a first motor configured for rotating the cutting tool aboutthe tool axis; and a radial offset mechanism configured for moving saidcutting tool in a radial direction such that the tool axis is offsetfrom a principal axis; and a second motor fixedly contained in thehousing and configured for rotating said pneumatic actuating assemblyand the cutting tool about the principal axis, said second motordisposed radially outwardly of and in substantially side by siderelation with said first motor relative to said principal axis such thatsaid first and second motors each extend longitudinally over an axiallinear extent such that there is a substantial amount of overlap of theaxial linear extents.
 7. The hand tool apparatus of claim 6, wherein thesecond motor is configured to rotate the pneumatic actuating assembly bymeans of a first gear wheel associated with the second motor, whichfirst gear wheel is used for rotating a second gear wheel associatedwith the pneumatic actuating assembly, said second gear wheel beingaxially displaceable relative to the first gear wheel.